Corrado Lucia, Ratti A, Gellera C, Buratti E, Castellotti B, Carlomagno Y, Ticozzi N, Mazzini L, Testa L, Taroni F, Baralle F E, Silani V, D'Alfonso S
Department of Medical Sciences, Interdisciplinary Research Center of Autoimmune Diseases (IRCAD), University of Eastern Piedmont, Novara, Italy.
Hum Mutat. 2009 Apr;30(4):688-94. doi: 10.1002/humu.20950.
Recent studies identified rare missense mutations in amyotrophic lateral sclerosis (ALS) patients in the TARDBP gene encoding TAR DNA binding protein (TDP)-43, the major protein of the ubiquitinated inclusions (UBIs) found in affected motor neurons (MNs). The aim of this study was to further define the spectrum of TARDBP mutations in a large cohort of 666 Italian ALS patients (125 familial and 541 sporadic cases). The entire coding region was sequenced in 281 patients, while in the remaining 385 cases only exon 6 was sequenced. In 18 patients, of which six are familial, we identified 12 different heterozygous missense mutations (nine novel) all locating to exon 6, which were absent in 771 matched controls. The c.1144G>A (p.A382T) variation was observed in seven patients, thus representing the most frequent TARDBP mutation in ALS. Analysis of microsatellites surrounding the TARDBP gene indicated that p.A382T was inherited from a common ancestor in 5 of the 7 patients. Altogether, the frequency of TARDBP gene mutations appears to be particularly high in Italian ALS patients compared to individuals of mainly Northern European origin (2.7% vs. 1%). Western blot analysis of lymphocyte extracts from two patients carrying the p.A382T and p.S393L TARDBP mutations showed the presence of lower molecular weight TDP-43 bands, which were more abundant than observed in healthy controls and patients negative for TARDBP mutations. In conclusion, this report contributes to the demonstration of the causative role of the TARDBP gene in ALS pathogenesis and indicates that mutations may affect the stability of the protein even in nonneuronal tissues.
近期研究在编码TAR DNA结合蛋白（TDP）-43的TARDBP基因中，发现了肌萎缩侧索硬化症（ALS）患者中的罕见错义突变，TDP-43是在受影响运动神经元（MNs）中发现的泛素化包涵体（UBIs）的主要蛋白质。本研究的目的是在666名意大利ALS患者（125例家族性和541例散发性病例）的大型队列中进一步确定TARDBP突变谱。对281名患者的整个编码区进行了测序，而在其余385例中仅对第6外显子进行了测序。在18名患者中，其中6名是家族性的，我们鉴定出12种不同的杂合错义突变（9种为新发现的），均位于第6外显子，在771名匹配对照中未发现这些突变。在7名患者中观察到c.1144G>A（p.A382T）变异，因此代表了ALS中最常见的TARDBP突变。对TARDBP基因周围微卫星的分析表明，7名患者中有5名的p.A382T是从共同祖先遗传而来。总体而言，与主要来自北欧的个体相比，意大利ALS患者中TARDBP基因突变的频率似乎特别高（2.7%对1%）。对两名携带p.A382T和p.S393L TARDBP突变患者的淋巴细胞提取物进行的蛋白质印迹分析显示，存在分子量较低的TDP-43条带，其比在健康对照和TARDBP突变阴性患者中观察到的更为丰富。总之，本报告有助于证明TARDBP基因在ALS发病机制中的致病作用，并表明突变可能即使在非神经组织中也会影响蛋白质的稳定性。
